Hasil untuk "Mineralogy"

V. V. Khrebtievsky, O. Yu. Plotinskaya

The paper describes the composition of skarn garnets of the Novonikolaevskoe Cu deposit (South Urals) in comparison with that of garnets of the Gumeshki and Tarutino skarn copper porphyry deposits in the Urals. Three generations of the andradite-grossular group garnets typical of skarn depositsare distinguished at the Novonikolaevskoe deposit. The median TiO2 content of garnet-1 and garnet-2 is 0.37 wt. % reaching 2.38 wt. % in garnet-3. This TiO2 content of garnets and relatively low Fe contents in some garnets from exoskarns (And40–54) possibly indicates a temperature increase during the skarn formation stage of garnets at the Novonikolaevskoe deposit, as well as relatively higher-temperature conditions of formation of garnet at the deposit compared to those from the Tarutino and Gumeshki deposits. Low fluid redox conditions during the formation of skarns at the Novonikolaevskoe deposit compared to the Tarutino deposit may be another reason for the low Fe contents in exoskarn garnets. According to the composition of garnet, the Novonikolaevskoe and Gumeshki deposits can be classified as Au-Fe-Cu skarn deposits, whereas the Tarutino deposit can be ascribed to a Cu-skarn deposit.

Zalewska Natalia, Leszek Czechowski

The research uses data from the Mini-TES infrared spectrometer of an Opportunity rover taken at selected locations along its route in Meridiani Planum on Mars. Using emissivity data, the corresponding mineralogical compositions were calculated. Generally, the results are consistent with previous works, in particular they indicate the widespread occurrence of clay minerals and minerals from basaltic rocks. However, several interesting facts were also noted. Among other things, clear changes in the hematite content were found, suggesting that certain area spherical concretions (known as blueberries) may be devoid of hematite. A similar phenomenon is known from studies of terrestrial concretions. Moreover, the possibility of pyrite existence was found on a certain section of the route. On Earth, pyrite often occurs with economically valuable minerals.

Olga N. Koroleva, Lyubov A. Nevolina, Sergey V. Rashchenko et al.

The crystallization of glasses used for immobilization of radioactive waste is generally undesirable due to potential disruption of the matrix structure with subsequent migration of radionuclides into the environment. However, glass crystallization, being a natural consequence of the establishment of equilibrium in the system, can be employed in the controlled synthesis of glass ceramics having predictable properties and structures. The paper discusses the results of crystallization in the glass-forming system Na2O-Cs2O-B2O3-SiO2 leading to the formation of ordered phases. During crystallization from borosilicate melt, cubic cesium borosilicate CsBSi2O6, as described in the space group I-43d, and orthorhombic Cs2B2Si3O10 (Cmce), were found with different Na2O/Cs2O ratios. A variety of techniques were employed to characterize the generated crystals. Single crystal x-ray diffraction (SXRD) was applied to identify the crystal structure. The crystalline arrangement of the crystals was confirmed using powder x-ray diffraction (PXRD) analysis. The Raman spectra and images of these crystalline phases are reported here for the first time.

C. Gunawardana, A. Goonetilleke, P. Egodawatta et al.

E. Garzanti, S. Andó, C. France‐Lanord et al.

Pablo Caballero, Sandra Macías-Benítez, Ana Moya et al.

Biostimulants are substances and/or microorganisms that are applied to plants or to the rhizosphere in order to enhance the natural process improving the absorption of nutrients and the quality of crops as well as the tolerance to abiotic stresses. A new biostimulant was developed from sewage sludge through its fermentation with <i>Bacillus licheniformis</i> as a plant growth-promoting bacteria (PGPB). The fermented product includes three classes of biostimulant components: the <i>B. licheniformis</i> biomass; the enzymatic secretion of said microorganism, which are mainly peptidases and amidases related to nitrogen metabolism and glucanases, related to carbohydrate metabolism; and finally, the hydrolyzed sludge organic matter, with a high content of protein hydrolysates. The biostimulant was evaluated in soil at the biochemical (enzymatic activities) and microbiological levels (metabarcoding analysis). Metabarcoding analysis revealed that the biostimulant complex, mainly the soluble fraction containing the <i>Bacillus</i> multienzyme complex and protein hydrolysate, induced PGPB soil bacteria, and it was detected that the inoculation in the soil of <i>B. licheniformis</i> remained active throughout the study. These results show the fermentation process with <i>B. licheniformis</i> as an interesting option for the total valorization of activated sewage sludge aimed at obtaining products of agronomic/environmental interest.

F. Jiang, F. Jiang, J. Song et al.

<p>The optical properties, chemical composition, and potential chromophores of brown carbon (BrC) aerosol particles were studied during typical summertime and wintertime at a kerbside in downtown Karlsruhe, a city in central Europe. The average absorption coefficient and mass absorption efficiency at 365 nm (Abs<span class="inline-formula">₃₆₅</span> and MAE<span class="inline-formula">₃₆₅</span>) of methanol-soluble BrC (MS-BrC) were lower in the summer period (1.6 <span class="inline-formula">±</span> 0.5 Mm<span class="inline-formula">⁻¹</span>, 0.5 <span class="inline-formula">±</span> 0.2 m<span class="inline-formula">²</span> g<span class="inline-formula">⁻¹</span>) than in the winter period (2.8 <span class="inline-formula">±</span> 1.9 Mm<span class="inline-formula">⁻¹</span>, 1.1 <span class="inline-formula">±</span> 0.3 m<span class="inline-formula">²</span> g<span class="inline-formula">⁻¹</span>). Using a parallel factor (PARAFAC) analysis to identify chromophores, two different groups of highly oxygenated humic-like substances (HO-HULIS) dominated in summer and contributed 96 <span class="inline-formula">±</span> 6 % of the total fluorescence intensity. In contrast, less-oxygenated HULIS (LO-HULIS) dominated the total fluorescence intensity in winter with 57 <span class="inline-formula">±</span> 12 %, followed by HO-HULIS with 31 <span class="inline-formula">±</span> 18 %. Positive matrix factorization (PMF) analysis of organic compounds detected in real time by an online aerosol mass spectrometer (AMS) led to five characteristic organic compound classes. The statistical analysis of PARAFAC components and PMF factors showed that LO-HULIS chromophores were most likely emitted from biomass burning in winter. HO-HULIS chromophores could be low-volatility oxygenated organic aerosol from regional transport and oxidation of biogenic volatile organic compounds (VOCs) in summer.</p> <p>Five nitro-aromatic compounds (NACs) were identified by a chemical ionization mass spectrometer (C<span class="inline-formula">₇</span>H<span class="inline-formula">₇</span>O<span class="inline-formula">₃</span>N, C<span class="inline-formula">₇</span>H<span class="inline-formula">₇</span>O<span class="inline-formula">₄</span>N, C<span class="inline-formula">₆</span>H<span class="inline-formula">₅</span>O<span class="inline-formula">₅</span>N, C<span class="inline-formula">₆</span>H<span class="inline-formula">₅</span>O<span class="inline-formula">₄</span>N, and C<span class="inline-formula">₆</span>H<span class="inline-formula">₅</span>O<span class="inline-formula">₃</span>N), which contributed 0.03 <span class="inline-formula">±</span> 0.01 % to the total organic mass but can explain 0.3 <span class="inline-formula">±</span> 0.1 % of the total absorption of MS-BrC at 365 nm in winter. Furthermore, we identified 316 potential brown carbon molecules which accounted for 2.5 <span class="inline-formula">±</span> 0.6 % of the organic aerosol mass. Using an average mass absorption efficiency (MAE<span class="inline-formula">₃₆₅</span>) of 9.5 m<span class="inline-formula">²</span>g<span class="inline-formula">⁻¹</span> for these compounds, we can estimate their mean light absorption to be 1.2 <span class="inline-formula">±</span> 0.2 Mm<span class="inline-formula">⁻¹</span>, accounting for 32 <span class="inline-formula">±</span> 15 % of the total absorption of MS-BrC at 365 nm. This indicates that a small fraction of brown carbon molecules dominates the overall absorption. The potential BrC molecules assigned to the LO-HULIS component had a higher average molecular weight (265 <span class="inline-formula">±</span> 2 Da) and more nitrogen-containing molecules (62 <span class="inline-formula">±</span> 1 %) than the molecules assigned to the HO-HULIS components. Our analysis shows that the LO-HULIS, with a high contribution of nitrogen-containing molecules originating from biomass burning, dominates aerosol fluorescence in winter, and HO-HULIS, with fewer nitrogen-containing molecules as low-volatility oxygenated organic aerosol from regional transport and oxidation of biogenic volatile organic compounds (VOC), dominates in summer.</p>

R. Seth Wood, Bryan C. Chakoumakos, Allison M. Fortner et al.

Abstract Otoliths are frequently used to infer environmental conditions or fish life history events based on trace-element concentrations. However, otoliths can be comprised of any one or combination of the three most common polymorphs of calcium carbonate—aragonite, calcite, and vaterite—which can affect the ecological interpretation of otolith trace-element results. Previous studies have reported heterogeneous calcium carbonate compositions between left and right otoliths but did not provide quantitative assessments of polymorph abundances. In this study, neutron diffraction and Raman spectroscopy were used to identify and quantify mineralogical compositions of Chinook salmon Oncorhynchus tshawytscha otolith pairs. We found mineralogical compositions frequently differed between otoliths in a pair and accurate calcium carbonate polymorph identification was rarely possible by visual inspection alone. The prevalence of multiple polymorphs in otoliths is not well-understood, and future research should focus on identifying otolith compositions and investigate how variations in mineralogy affect trace-element incorporation and potentially bias environmental interpretations.

H. Nesbitt, R. Wilson

R. Mitchell

Khalid A. Alshibli, M. Cil

Wayne Nesbitt, C. Fedo, G. M. Young

H. Jamieson, S. Walker, M. Parsons

C. Giacovazzo

O. Braissant, G. Cailleau, C. Dupraz et al.

HongFeng Yang, XiaoWei Chen, Rebecca Harrington et al.

Michael E. Deary, Patrick M. Amaibi, John R. Dean et al.

Aqueous modelling of chemical speciation in simulated lung fluid (SLF) enables a better understanding of the underlying chemical factors that influence metal(loid) inhalation bioaccessibility from airborne particulate matter. Such an approach can be used to supplement experimental techniques that are integral to the health risk assessment of metal(loid) exposure by inhalational routes. In this paper, we modelled the aqueous chemistry of airborne particulate-bound metal(loid)s (As, Cu, Mn, Pb and Zn) in a SLF based on Gamble’s solution (neutral pH). The modelling was performed using two software packages (Geochemist’s Workbench 14 and OLI Studio 9.5) and a total of five thermochemical databases (GWB Thermo, MINTEQ, PHREEQC, WATEQ4F and the default database for OLI Studio). Modelled results were compared with experimentally determined bioaccessibilities for the NIST 2710a standard reference material (SRM) and with literature-reported bioaccessibilities for NIST 1648a and BCR 038 SRMs. Whilst the models correctly describe the observed increase in bioaccessibility for more dilute solid/liquid extraction ratios, the performance of the models against the fractional bias of the mean (<i>FB_mean</i>) and the normalised mean square error (NMSE) statistical metrics was generally outside the acceptance criteria. Findings from an analysis of the main aqueous chemical species predicted to be present in SLF indicate that carbonate and chloride complexes of Cu, Mn, Pb and Zn predominate, whilst free cations (for Cu, Mn and Zn) and hydroxides (for Cu) also play a role in solubilisation. Arsenic is not predicted to form significant complexes with the SLF components and is present in solution mainly as the HAsO₄²⁻ ion and its conjugate acid, H₂AsO₄⁻. For modelled runs where glycine and citrate were present, significant increases in the bioavailability of Cu and Zn were predicted as a result of complexation with these ligands. An additional finding from our experimental bioaccessibility results for NIST 2710a was that the inclusion of the lung fluid surfactant dipalmitoylphosphatidylcholine (DPPC) in the SLF did not significantly affect the bioaccessibility. Our study provides useful insights into the likely aqueous- and solid-phase speciation of metal(loid)s in SLF and highlights that future developments in this area should consider the role of mineralogy and surface interactions.

C. S. J. Shaw

<p>Granulite xenoliths from the Quaternary West Eifel Volcanic Field in Germany record evidence of magmatism in the lower crust at the end of the Permian. The xenoliths sampled two distinct bodies: an older intrusion (ca. 264 Myr old) that contains clinopyroxene with flat, chondrite-normalised rare earth element (REE) profiles and a younger (ca. 253 Myr old) intrusion that crystallised middle-REE-rich clinopyroxene. The younger body is also distinguished based on the negative Sr, Zr and Ti anomalies in primitive mantle-normalised multi-element plots. REE-in-plagioclase–clinopyroxene thermometry records the magmatic temperature of the xenoliths (1100–1300 <span class="inline-formula">^∘</span>C), whereas Mg-in-plagioclase and Zr-in-titanite thermometry preserve an equilibration temperature of ca. 800 <span class="inline-formula">^∘</span>C. These temperatures, together with a model of the mineral assemblages predicted from the composition of one of the xenoliths, define the pressure of crystallisation as <span class="inline-formula">∼1</span> GPa. The xenoliths also preserve a long history of reheating events whose age ranges from 220 to 6 Myr. The last of these events presumably led to breakdown of garnet; formation of symplectites of orthopyroxene, plagioclase and hercynite; and redistribution of heavy rare earth elements into clinopyroxene. The data from the West Eifel granulite xenoliths, when combined with the existing data from granulites sampled in the East Eifel, indicate that the lower crust has a long a complex history stretching from at least 1.6 Ga with intrusive events at ca. 410 and 260 Ma and reheating from the Triassic to late Miocene.</p>

K. Kohfeld, S. Harrison

A. Hood, M. Wallace